Abstract: Using the O216 synthesized in laboratory and 3^# inert solvent as the extraction solution and the leaching solution from sodium roasting of V-Cr slag as raw material,the effects of pH of the leaching solution,concentration of the extraction solution,extraction temperature,extraction time and phase ratio on the separation efficiency of V and Cr were studied.The saturation capacity of the extraction solution under the optimum conditions was determined.The optimum conditions are shown as follows:the leaching solution pH of 1.8,the volume concentration of 40% for the extraction solution,the extraction temperature of 30℃,the extraction time of 5 min,and the phase ratio of 1:1.The single stage extraction rate of vanadium and chromium are 98.79% and 36.42% respectively,with the separation factor at 142.90.The saturation capacity of O216 extraction solution for vanadium and chromium is respectively 41.46 g/L of V₂O₅ and 3.62 g/L of Cr₂O₃.It shows an effective separation of vanadium and chromium in the extraction solution of O216-3^# inert solvent.